This invention relates to polyamide compositions having improved flame retardant properties.
This use of polyamide resins in molding compositions has become very widespread in recent years especially in end uses where toughness and high temperature stability are required properties. Speciality polyamide resins containing a variety of filler materials have been widely used in a range of automotive applications for example and other polyamides have been successfully introduced into the electrical, appliance and consumer goods fields.
Where the end-use requires a molding composition, it is a common practice in the art to treat the resin with a small amount of a mold release agent and one such agent, among the many described in the literature, is stearyl alcohol (disclosed in British Pat. No. 851,031). Unfortunately it has been found that the use of such alcohols has a deleterious effect on the flammability of the nylon and this is becoming, for many uses, a vital factor in achieving customer acceptability. It is also known that aluminum salts of fatty acids can be used as lubricants for polyamides and alumnium stearates are widely used for this purpose.
It has now been discovered that a certain combination of such mold release and lubricant additives not only provides the expected desirable mold release improvements in the polyamide but also gives a product that, surprisingly and unpredictably, has also good flame-retardant characteristics.